A widely known moisture and heat exchange device for a breathing respiratory apparatus in the form of a breathing gas conditioner (cf. U.S. Pat. No. 3,747,598, Int. Cl. A62 B 7/06, 1970) comprises hydrophobic elements in the form of copper wire nets exhibiting high heat conductance and hydrophilic elements or hygroscopic means in the form of activated molecular sieve means therebetween. In this moisture and heat exchange apparatus the exhaled air passes through the multiple-layer package of hydrophobic and hydrophilic elements in the form of the nets and molecular sieves. The exhaled air is dried owing to adsorption of water vapour in the porous structure of the hydrophilic elements. The inhaled air passes through the multiple-layer package of hydrophobic and hydrophilic elements and is cooled by transfer of the part of heat to the hydrophobic members or copper wire nets and to evaporation of moisture adsorbed by the hydrophilic elements in the form of molecular sieves. This results in moistening of the inhaled air.
The above described moisture and heat exchange device for a breathing apparatus exhibits a low efficiency since by the end of operation of the apparatus, as the temperature of the hydrophilic elements, in the form of molecular sieves increases, physical adsorption of moisture in the hydrophilic elements is impaired and the air flow is redistributed as a result of the non uniform saturation of the hydrophilic elements adsorbent with moisture.
Another widely known moisture and heat exchange device for a breathing apparatus (cf. Japanese patent specification Nos. 56-53381, Int. Cl. A. 61 M/16/00, A62 B 7/00, 1977) comprises a casing in the form of a tubular member accomodating a multiple-layer package of alternating hydrophobic elements in the form of metal heat conducting members and hydrophilic elements in the form of moisture-adsorbing heat insulating members. The hydrophobic and hydrophilic elements in this device are made in the form of washers. The hydrophobic elements are made of braided metal nets.
The abovedescribed moisture and heat exchange device for a breathing apparatus exhibits low efficiency owing to impaired conditions for the flow of inhaled and exhaled air through and around the hydrophobic elements in the form of heat conducting metal fibers. This is due to the fact that the process of heating and cooling of the hydrophobic elements is a long-term process and the time of heat exchange between the inhaled and exhaled air on the one side and the hydrophobic elements on the other during inhalation and exhalation is short (from 0.3 to 0.5 s). Since the heat conducting members of a breathing apparatus are heated to the maximum extent by the end of operation of the apparatus, and their temperature is close to that of the air admitted from a breathing bag, this time is not long enough for efficient cooling of the inhaled air.
Conditions for the flow of inhaled and exhaled air around the heat insulating fibers of the hydrophilic elements impregnated with a chemical adsorbent are also impaired, an increase in the adsorbent temperature having no effect on the moisture adsorbing capacity. Such adsorbent, applied to a support in the form of a washer made of a fibrous material, include hygroscopic salts such as CaCl.sub.2, LiCl, ZnCl.sub.2 which form crystallohydrates when adsorbing moisture. A layer of a solution of the hygroscopic substance is formed on the surface of the hydrophilic elements and covers the pores of both the hydrophilic elements and the adjacent hydrophobic elements. Clogging of pores of the hydrophobic and hydrophilic elements with a solution of the hygroscopic substance results in a redistribution of the air flow and non-uniform absorption by the adsorbent on the hydrophilic elements.